1. Field of the Invention
The present invention relates to a speed control for an electric motor. In particular, the present invention relates to a pulse width modulation speed control for a DC electric motor.
2. Description of the Prior Art
Pulse width modulation is a technique which has been used in a variety of fields, including communications and electrical controls. Pulse width modulation may be used to power DC motors by using a pulse train instead of a variable DC voltage level to control motor speed. The width of the pulses of the pulse train correspond to the time it takes for the motor to attain a specific velocity while applying a full amplitude DC voltage, while never allowing the motor to attain full speed as defined by a continuous DC voltage signal. This method provides full voltage-like torque without full speed and also eliminates the hunting associated with motor startup which occurs with variable voltage speed control of DC motors.